Emergence 101

Everything's connected but you already know that, right? It seems murmurations of millions of starlings and cilia of a tiny animal known as Trichoplax adhaerens move exactly the same way even though Trichoplax has neither a brain nor muscles to "walk" is cilia in similar fashion to how starlings mass and move as one through skies all over the world.

In a trio of preprints totaling more than 100 pages — posted simultaneously on the arxiv.org server last year — he and Bull showed that the behavior of Trichoplax could be described entirely in the language of physics and dynamical systems. Mechanical interactions that began at the level of a single cilium, and then multiplied over millions of cells and extended to higher levels of structure, fully explained the coordinated locomotion of the entire animal. The organism doesn’t “choose” what to do. Instead, the horde of individual cilia simply moves — and the animal as a whole performs as though it is being directed by a nervous system. The researchers even showed that the cilia’s dynamics exhibit properties that are commonly seen as distinctive hallmarks of neurons.

And the synchronized orientation patterns could be complex: Sometimes the activity of the system produced vortices, with the cilia oriented around a single point. In other cases, the cilia reoriented in fractions of a second, first pointing one way and then another — flocking as a group of starlings or a school of fish might, and resulting in an agility that made it possible for the animal to sometimes change direction on a dime.

“We were just jaws-on-the-floor surprised when we first saw these cilia reorienting in second timescales,” Bull said.

This magnified side view of Trichoplax crawling across a surface shows how the thousands of cilia on its underside move with a walking gait. The collective movements of the cilia are coordinated entirely by mechanical interactions. Prakash Lab

Emergence 101 indeed.